Mechanically operated eraser for typewriters



May 16, 1939. c goL s 2,158,534

MECHANICALLY OPERATED ERASER FOR TYPEWRITERS 2 Shee*ts$heet 1 Original Filed Jan. 14, 1937 y 1939- c. *r. COLLINS 2,158,534

MECHANIGALLY OPERATED ERASER FOR TYPEWRITERS Original Filed Jan. 14, 1937 2 Sheets-Sheet 2 ATTORN EYS Patented May 16, 1939 UNHTED STATES MECHANIOALLY OPERATED ERASER FOR TYPEWRITERS Charles T. Collins, Reubens, Idaho Application January 14, 1937, Serial No. 120,584 Renewed November 2, 1938 9 Claims.

My present invention relates to the art of typewriter accessories and more particularly to a mechanically operated eraser for typewriters.

It has been found by study and analyses that by far the largest amount of time spent by stenographers in making erasures on typewritten copy is for erasures involving single letters or characters. The next erasure that occurs with the greatest frequency is where two letters are transposed. Now, in making such erasures it is customary for a stenographer who prides herself on the neatness of her copy, to use an erasing shield so that, as the eraser is applied, only the letter to be erased will be affected. This requires time; the turning back of the roll, the placing of the shield, and the actual erasing. This general problem has been recognized by others andvarious attempts have been made to solve it.

In my present invention I have produced a device of such a character, but one which is mechanically operated by a single key similar to a type bar key; the device is simple in construction, and effective in operation. When used the operator is assured that only the character in question will be disturbed, and that the adjoining letters, or characters will not be smudged. This certainty of operation enables the use of the device with dispatch and confidence.

Other and more specific objects will be apparent from the following description taken in connection with the accompanying drawings, wherein Figure 1 is a perspective view showing a portion of a typewritenwith my device installed thereon. v

Figure 2 is a longitudinal, sectional view through my eraser proper as it appears in its normal position, the cutting plane being taken substantially horizontal.,

Figure 3 is a view similar to Figure 2 except that the cutting plane is taken substantially in the vertical and, for clearness, the device is shown in its operating position abutting a typewriter roller.

Figure 4 is a perspective view showing a portion of the actuating mechanism and its toggle linkage.

Figure 5 is a bracketed view showing, in a fragmentary elevation, the operating mechanism for my eraser together with a typewriter roller and a single type bar so as to better illustrate the relationship between my device and the typewriter parts.

Figure 6 is a cross-sectional view taken along line 6-6 of Figure 3 showing the jaw member disengaged from the screw threads as occurs when the eraser revolves or is returning to its original position.

Figure 7 is a cross-sectional View taken alon line 1-1 of Figure 5 showing the jaw members 5 engaging the screw threads of the spring winding shaft.

Figure 8 is a cross-sectional view taken along line 8-8 of Figure 3 showing the central shaft released from the jaw members and the pawl dis- 10 engaged from its ratchet.

Figure 9 is a cross-sectional view taken alon line 9-9 of Figure 5 showing the coil spring which supplies the rotatable power to the eraser.

Figure 10 is a vertical, cross-sectional view 15 taken along line l0l0 of Figure 2 showing the pawl and ratchet used to hold the eraser revolving coil spring in its wound position.

Referring to the drawings, throughout which like reference characters indicate like parts, I2 20 designates the cylindrical housing for my erasing mechanism. This is secured, by any convenient form of bracket 14, in a position so that its axis extended will meet typewriter roll I5 at the same point the type hits. .Coaxially disposed within 25 housing I2 is the screw shaft IS. The general nature of this screw follows the principles of de-- sign employed in the push type screw drivers and drills where the screw is caused to revolve by engagement with the jaws on longitudinal 30 movement. Screwed to the outer end of screw shaft I6 is theeraser holding device l8. This should be attached to screw l6, as by a set screw [9, so that the unit can be removed for easy replacement of the eraser proper 20. This eraser 35 should be of the type commonly supplied with mechanical pencils wherein the rubber itself is preferably encased at its lower end in a metal cup 2|. I have, further, provided a compression spring 22 to assure a constant application of 40 spring pressure to the eraser 20 while it is performing the erasing operation.

Shaft I6 is journaled at its opposite end in the spring housing 24, being provided with spaced bearings at 25 and 26. Within housing 24 is dis- 4;, posed the eraser revolving spring 28. This structure follows the general principles of clock springs although it need not necessarily be made of fiat material. Spring 28 has its inner end secured to shaft I6 as at 30; its other end is secured as by 5 pillar 32 to housing 24 which housing in turn is free to reciprocate within housing l2 but is prevented from revolving by its operating arm 38 which operates within slot 40 cut in the body of housing I 2. A ratchet 34, fixedly secured to shaft 55 I8, is disposed to engage pawl 35 so as to retain the tension in spring 28. Pawl 35 has a torsion spring 86 which assures its being in engagement with ratchet 34 except during the period it is released by other means.

To provide rotation for shaft l6 and. thus to wind up spring 28 I provide a pair of jaw members 42 and 43 pivoted at 45 and 46, respectively, to brackets which in turn are fixedly secured to housing I 2. These jaw members have curved engaging portions 41 and 48 disposed at such an angle as to properly engage thread 50, of shaft l6, and have the proper curvature so that they will fit well into the thread. Torsion springs are provided at their pivot points so as to normally urge the jaws into engagement with thread 58. Inasmuch as it is desired that the two jaw members act together in both engaging and releasing shaft I6 I have provided toggle links 52 and 53 pivoted to jaw members 42 and 43, respectively, at one end, and pivotally joined together at 54. A release follower 56 is provided for actuating this linkage in a manner to be more fully explained under the operation of this device. Follower 56 is disposed to engage, at the proper time, cam 58 which is formed as part of shaft I 6.

To energize my eraser I provide a key lever 60 pivoted as at 6| to the typewriter frame. This lever acting against spring 62 operates the connecting link 63. This link, in turn, is pivotally connected to the bell crank 65 which is pivotally supported at 66 from the typewriter frame 68. The upper end of bell crank 65 is bifurcated so as to operatively engage post 18 formed as part of the operating arm 38.

Method of operation In using my device the operator need only back space, or otherwise move the carriage, so

that the defective letter is at the point of type contact; then, by depressing key bar 68 and releasing the same, the erasing operation is completed. During this operation the eraser has been moved forward until it is in contact with the paper at the point indicated in Figure 1 by the dotted circle at H, shaft l6 has been revolved to wind up coil spring 28 and the same has been released atits outer extreme position so that spring 28 can spin the eraser when it is in contact with the paper and thus remove the unwanted character.

The step by step operation is substantially as follows: when bar 60 is depressed the connecting linkage moves arm 38 which is secured to housing 24 forwardly in slot 40. The jaw members 42 and 43 are engaged with the threads of shaft l6 and as the whole assembly is moved to the left as viewed in Figures 2, 3, and 5, shaft I6 is revolved thus winding up and storing within spring 28 sufficient energy to revolve the eraser the desired amount. This spring tension, created by the revolving shaft I6, is held by pawl 35 engaging ratchet 34. When shaft l6 has progressed sufficiently along housing l2, cam 12 secured to housing 24, engages links 52 and 53 between their fixed pivot points and forces them in toward shaft l6 thus causing the toggle linkage to pass its center line after the showing of Figure 7 in which the operation is started and Figure 8 where the operation is completed. This action withdraws jaw members 42 and 43 from engagement with shaft l6. As this movement is being completed jaw member 42, in moving upwardly, engages bar 14, which is part of pawl 35;

when so engaged pawl 35 is lifted and released from engagement with ratchet 34 permitting spring 28 to expend its energy in revolving shaft l6 and eraser 28 carried by it. The exact number of turns is a matter of design, it being found that four to flve complete revolutions of eraser 20, if the eraser is made of suitable material, is suflicient for a good, clean erasure of the average typewritten character. The torsion springs acting at pivot points 45 and 46, normally tending to close jaw members 42 and 43, serve to maintain links 52 and 53 in the position shown in Figure 8, during this stage of the operation. As the mechanism, however, is restored to the original position as shown in Figure 2 and Figure 5 it is necessary to trip this toggle so as to restore the mechanism to the position of engagement as shown in Figure 7. This is accomplished in the final return of shaft l6 by means of the cam follower 56 which during .the return movement has been lying close against shaft 16. This follower has a beveled end which engages cam surface 58, a part of shaft l6, and is pressed outwardly. Inasmuch as the follower 56 is secured to link 53 near its center pivot point it moves this pivot point outwardly as indicated in Figure '7 thus restoring the jaw members to their operative, or engaged, position.

While the operation of this mechanism required a rather lengthy explanation it functions very quickly, with no attention from the operator other than the pressing of key bar 60 and then releasing the same after contact has been made with the roller l5. If it is necessary to erase an entire word it is only necessary to press the key once for each letter to be erased and in this manner even a rather long word will be erased more quickly and more neatly than could be done by means of the conventional type of typewriter eraser and eraser shield.

The foregoing description and the accompanying drawings are believed to clearly disclose a preferred embodiment of my invention but it will be understood that this disclosure is merely illustrative and that such changes in the invention may be made as are fairly within the scope and spirit of the following claims.

I claim:

1. In an erasing attachment, the combination with a fixed casing having a pair of opposed spring-pressed jaws, and means for opening the jaws, of a reciprocable non-rotary motor housing in the casing and means for reciprocating the housing, a screw shaft journaled in the housing and a spring-motor operatively connecting the shaft and housing, said jaws and shaft co-acting to wind the motor as the housing is projected, retaining means for the wound motor, and means for releasing the retaining means to permit operation of the motor.

2. In an erasing attachment, the combination with a fixed casing, a reciprocable non-rotary motor housing in the casing, and means for reciprocating said housing, of a screw shaft journaled in the housing and co-acting means mounted in the casing for revolving said shaft, a spring-motor mounted in the housing and connected with the shaft, retaining means for the wound motor, and means for releasing the retaining means to permit operation of the motor.

3. man erasing attachment, the combination with a fixed casing, a non-rotary housing reciprocable in the casing, and means for reciprocating the housing, of a rotary shaft journaled in the housing and co-acting means on the shaft and housing for revolving the shaft as the housing is projected, a ratchet on the shaft and a spring-pawl on the housing, a spring-motor having its ends fixed to the shaft and housing, and means for releasing the pawl at the end of the working stroke of the housing to permit operation of the motor.

4. In an erasing'attachment, the combination with a fixed casing having a pair of opposed spring-closed jaws, of a reciprocable non-rotary motor housing in the casing, and means for reciprocating the housing, of a screw shaft journaled in the housing and engaged by said jaws whereby the shaft is revolved as the housing and shaft are projected, a spring-motor attached to said shaft and housing, a ratchet connection between the shaft and housing, means for opening the jaws at the end of a projecting stroke of the housing and shaft, and means for releasing the ratchet to permit operation of the spring motor.

5. In an erasing attachment, the combination with a fixed casing, a non-rotary housing reciprocable in the casing, and means for reciprocating the housing, of a rotary shaft journaled in the housing and co-acting means on the shaft and casing for revolving the shaft as the housing and shaft are projected, a spring motor in the housing operatively connecting said housing with the shaft, a ratchet device for retaining the motor in wound position, a cam-disk rigid with the shaft and means co-operating therewith to release the co-acting means, and means for releasing the ratchet device.

6. In an erasing attachment, the combination with a fixed casing, a reciprocable non-rotary housing in the casing, and a depressible keylever mechanism for projecting the housing, of a screw-shaft journaled in the housing, a pair of opposed spring-closed jaws in the casing for coaction with the screw shaft, and toggle-mechanism for opening said jaws, a spring connected at its ends to the shaft and housing and means for retaining the spring under tension, means for actuating the toggle mechanism, and means for releasing the retaining means.

7. In an erasing attachment of the rotaryreciprocating type, the combination with a pair of opposed, spring-closed jaws having stationary pivotal supports, and a toggle-linkage between said jaws, of a non-rotary reciprocable member having a cam for co-action with the linkage to open said jaws, a follower-arm rigid with one of the toggle links, and a cam-disk on a rotaryreciprocable member for co-action with said arm to permit restoration of the jaws to closed position.

8. In an erasing attachment, the combination with a fixed casing, a pair of opposed springclosed jaws pivoted in the casing, a toggle linkage connecting said jaws, and a follower arm rigid with one link of the toggle, of a rotaryreciprocable screw shaft with which said jaws are engaged and a reciprocable support for the shaft, a cam mounted on said support for coaction with the linkage to open the jaws, and a cam-disk rigid with the shaft for co-action with the follower arm to permit closing of the jaws.

9. In an erasing attachment, the combination with a fixed casing, a reciprocable non-rotary motor housing in the casing, and means for reciprocating the housing, of a screw shaft journaled in the housing, an eraser having a resilient support on the free end of the shaft, co-acting means in the casing for engagement with the screw shaft to revolve the shaft as the latter is projected, a spring-motor having its ends connected to the shaft and housing, means for retaining the wound motor, and means for releasing the wound motor to impart rotary movement to the eraser.

Witnesses to mark: F. K. DAIDIARELL, Mas. A. B. MCCRIIADY. 

